CIE iGCSE Co-Ordinated Science P3.2.4 Dispersion of light Exam Style Questions Paper 1
▶️ Answer/Explanation
When light travels from air into a denser medium like glass, it slows down and bends towards the normal. The angle of incidence (\(i\)) is the angle between the incident ray and the normal, while the angle of refraction (\(r\)) is the angle between the refracted ray and the normal. Since the light bends towards the normal, \(r\) is smaller than \(i\). Diagram B correctly shows the light bending towards the normal with \(i\) and \(r\) correctly labelled.
✅ Answer: (B)
✅ Answer: (B)
▶️ Answer/Explanation
When light enters a glass block from air, it slows down and bends towards the normal (refraction). When it leaves the glass block back into air, it speeds up and bends away from the normal, emerging parallel to its original direction but laterally displaced. Arrow C correctly shows this path.
✅ Answer: (C)
✅ Answer: (C)
▶️ Answer/Explanation
Angle X is measured between the incident ray and the normal, so it is the angle of incidence. Angle Y is measured between the refracted ray (the ray that has passed into the water) and the normal, so it is the angle of refraction. Reflection would involve a ray bouncing off the surface back into the same medium, which is not shown in the diagram. Therefore, option B correctly identifies angle X as the angle of incidence and angle Y as the angle of refraction.
✅ Answer: (B)
✅ Answer: (B)
▶️ Answer/Explanation
The angle of incidence is measured between the incident ray and the normal (the line perpendicular to the mirror surface).
If the angle between the ray and the mirror surface is 40°, then the angle with the normal is \(90° – 40° = 50°\).
✅ Answer: (B)
If the angle between the ray and the mirror surface is 40°, then the angle with the normal is \(90° – 40° = 50°\).
✅ Answer: (B)
▶️ Answer/Explanation
The focal length is the distance between the centre of the lens and the principal focus (focal point). In the diagram, this is the distance from the lens to where the rays converge after passing through the lens. The other labelled distances represent object distance and image distance.
✅ Answer: (B)
✅ Answer: (B)